2.5 is not that bad. you could try adding a DNase treatment step on the membrane before eluting. if you already use a DNase step, try entending the time to see if you get better 260/230 ratios
high 260/230 can be caused by phenolic residue, thiocyanates ( left over from the purification process) or physically by zeroing the spectrometer with a blank that is not matching exactly the constitution and pH of the solvent that the rna is dissolved in